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Radioisotope System Keeps Mars Rover Moving

Tuesday, 11 June 2013

The instruments aboard NASA’s Mars Science Laboratory
“Curiosity” rover receive their power from a radioisotope system
assembled and tested at Idaho National Laboratory. The Multi-
Mission Radioisotope Thermoelectric Generator is a “space battery”
that can reliably power a deep space mission for many years.

The generator provides 110 Watts of electricity, as well as a
continuous source of heat and power for the Curiosity rover’s
instruments. The power system will enable Curiosity to complete
its ambitious expedition in Mars’ extreme temperatures
and seasons. The nuclear fuel is protected by multiple layers
of safety features that have each been rigorously tested under
varied accident scenarios.

Other tests included vibrational testing to simulate rocket
launch conditions, magnetic testing to ensure the system’s
electrical field did not affect the rover’s sensitive scientific
equipment, mass properties tests to determine the center of
gravity, and thermal vacuum testing to verify operation on a
planet’s surface or in the cold vacuum of space.

The system will supply warmth and electricity to Curiosity
and its scientific instruments using heat from nuclear decay.
The generator is fueled with a ceramic form of plutonium
dioxide encased in multiple layers of protective materials,
including iridium capsules and high-strength graphite blocks.
As the plutonium naturally decays, it gives off heat, which is circulated
through the rover by heat transfer fluid plumbed
throughout the system. Electric voltage is produced by using
thermocouples, which exploit the temperature difference
between the heat source and the cold exterior.

The nuclear-powered rover travels farther, lasts longer, and
powers and heats a larger and more capable scientific payload
compared to the solar power alternative studied by NASA.
NASA has used nuclear generators to safely and reliably power
26 missions over the past 50 years.

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